Files
amethyst/quartz/src
Claude 36a7ae147e fix: reduceWide round-2 carry overflow — fixes NIP-44 conversation key for edge-case scalars
The 4×64-bit reduceWide in FieldP had a bug: round 2 carry propagation
could overflow past 256 bits when out[0..3] were all 0xFF...FF, silently
dropping the overflow. This caused field multiplication results to be
off by exactly C = 2^32 + 977, corrupting point arithmetic for specific
intermediate values (e.g. ECDH with scalar n-2 on small x-coordinates).

Fix: detect round-2 overflow and fold the extra bit (≡ C mod p) back in.
Also fix ktlint violations in ScalarN and update documentation.

https://claude.ai/code/session_01BhU63WUe9AhikZxRdw3Lpg
2026-04-06 13:12:18 +00:00
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